OBJECTIVE: The main objective of this project is to determine the primary, tertiary, and quaternary structure of some of the enzymes concerned with the synthesis of heme, vitamin B12 and chlorophyll. Furthermore, our studies on these enzymes have led us to analyze subunit-subunit interactions for the elucidation of the structure, and the functional unit of the enzymes may lead to a better understanding of the function of these enzymes under different cellular conditions or under different environmental conditions. Along with these structure-function relationships we have continued our efforts to uncover greater details of the enzymic mechanism. The goals we had set for the current year were to determine the primary and quaternary structure of alpha-aminolevulinic acid dehydratase, possibly a beginning in the pursuit of the tertiary structure of the dehydratase, and the control of the functioning of alpha-aminolevulinic acid synthetase. APPROACH: We have purified and crystallized alpha-aminolevulinic acid dehydratase and have isolated peptides by both enzymic and chemical methods. The sequence of the amino acids in the peptides is being determined. Other studies on the dehydratase involve the formation of an immobilized derivative and studies which cause dissociation and association of the enzyme. Hybridization studies with subunit derivatives derived by acylation are also investigated among many other approaches. BIBLIOGRAPHIC REFERENCES: Porphyrin Synthesis: Some Particular Approaches. David Shemin, Annals of the New York Academy of Sciences, 244, 348 (1975). Delta-Aminolevulinic Acid Dehydratase: Structure, Function and Mechanism. David Shemin. Philosophical Transactions of the Royal Society. B 273, 109 (1976).